TY - JOUR
T1 - Energy reserve modification in different age groups of Daphnia schoedleri (Anomopoda: Daphniidae) exposed to hexavalent chromium
AU - Arzate-Cárdenas, Mario Alberto
AU - Martínez-Jerónimo, Fernando
N1 - Funding Information:
M.A. Arzate-Cárdenas is grateful for financial support received from CONACYT (fellow No. 205561) and the Programa Institucional de Formación de Investigadores (PIFI) of the Comisión de Operación y Fomento de Actividades Académicas del IPN (COFAA). F. Martínez-Jerónimo is grateful to the Sistema de Estímulo al Desempeño de los Investigadores (EDI) and COFAA (IPN-Mexico) for financial support granted.
PY - 2012/7
Y1 - 2012/7
N2 - Caloric content is a reliable biomaker of effect since it is modified by exposure to toxicants that can alter basal metabolism. Since organisms' age modifies how energy resources are allocated and modifies the activity of antioxidant enzymes, the response to toxic agents could be altered with age. Seven age groups of Daphnia schoedleri (0, 3, 5, 7, 14, 21, and 28-day-old) were exposed for 24h to two sublethal concentrations of Cr(VI): 1/25 and 1/5 of the 48h EC 50 of each age group, to determine the age at which susceptibility to Cr(VI) is highest. To evaluate energy content, carbohydrate, protein and lipid reserves were quantified and antioxidant enzymes activity was assessed (SOD, CAT, GPx, and GR). Furthermore, an integrative approach was applied to evaluate both sets of responses and interpret them as a whole in a simply visual way, achieved by the integrated biomarker response approach. Results indicate that Cr(VI) induced significant differences in all age groups. Seven and 14-day-old organisms were exposed to the highest concentrations (based on their EC50) and showed greater tolerance to this metal. Susceptibility to the toxicant was highest in younger specimens in which energy requirements are greater due to high growth rates (basal metabolism), as a result of which more energy reserves are expended to satisfy demands in terms of growth and response to toxicants.
AB - Caloric content is a reliable biomaker of effect since it is modified by exposure to toxicants that can alter basal metabolism. Since organisms' age modifies how energy resources are allocated and modifies the activity of antioxidant enzymes, the response to toxic agents could be altered with age. Seven age groups of Daphnia schoedleri (0, 3, 5, 7, 14, 21, and 28-day-old) were exposed for 24h to two sublethal concentrations of Cr(VI): 1/25 and 1/5 of the 48h EC 50 of each age group, to determine the age at which susceptibility to Cr(VI) is highest. To evaluate energy content, carbohydrate, protein and lipid reserves were quantified and antioxidant enzymes activity was assessed (SOD, CAT, GPx, and GR). Furthermore, an integrative approach was applied to evaluate both sets of responses and interpret them as a whole in a simply visual way, achieved by the integrated biomarker response approach. Results indicate that Cr(VI) induced significant differences in all age groups. Seven and 14-day-old organisms were exposed to the highest concentrations (based on their EC50) and showed greater tolerance to this metal. Susceptibility to the toxicant was highest in younger specimens in which energy requirements are greater due to high growth rates (basal metabolism), as a result of which more energy reserves are expended to satisfy demands in terms of growth and response to toxicants.
KW - Aquatic ecotoxicology
KW - Cladoceran
KW - Energy reserves
KW - Integrated biomarker response
KW - Oxidative stress
UR - http://www.scopus.com/inward/record.url?scp=84859190437&partnerID=8YFLogxK
U2 - 10.1016/j.etap.2012.03.003
DO - 10.1016/j.etap.2012.03.003
M3 - Artículo
C2 - 22481114
SN - 1382-6689
VL - 34
SP - 106
EP - 116
JO - Environmental Toxicology and Pharmacology
JF - Environmental Toxicology and Pharmacology
IS - 1
ER -